Hi all, I work with oSoMoN, just jumping in to add some thoughts to the conversation.
This is quite true, but it means you have to sacrifice having the features of a modern library version for the convenient or portability, or sacrifice portability to gain the features. Bundling those libraries means you get to keep both, while only sacrificing a little disk space. The build tools (snapcraft) also make it considerably easier than trying to build against an old library.
Indeed, with snaps being bind-mounted squashfs filesystem images, they can sometimes take up less disk space than a traditional package that is extracted on install.
They don't have to, as I said above the build tools make it easy to do, and in most cases re-running the build script is all that's needed to get the latest (fixed) version of those dependencies either from your distro or directly from upstream. For an actively developed application, this isn't going to be a problem for the developers or users. And, as oSoMoN mentioned already, snapped apps are run in a sandbox, so even for apps that don't get updated regularly, they won't be able to damage the user's system.
